Kona UTE Cargo Ebike

[E-tilitarian]

Hello Endless Sphere! i picked up this Kona UTE for $300cad and am hoping to turn it into a versatile car replacement. I have 6x 36v 9ah LFP modules i am planning on using with it. I have not decided it if i will run at 36v or 72v. I would like to be able to go up to 45kph while unloaded.
I plan on hauling lots of gear and probably a trailer, these times i am not concerned about speed and will probably keep under 32kph. I am hoping to be able to run my small landscaping business off of this bike, as well as commuting and 'road trips'.

I am 90% sure i want a direct drive hub motor instead of a mid drive. The stock wheels are both 29". I will be replacing the front wheel with a 26" 2.8" tire. Disc brake in the front.
I understand with a direct drive i am better off having the wheel smaller. This bike has a rim brake in the rear so i dont think i can adapt it to a smaller wheel.
This will leave me with regenerative braking as my only form of braking.

Is it safe to run a bike with regen as the only rear brake?

If it is safe to do so, my plan is to run a 24" wheel with a fat tire that will mimic the rough proportions of a 26" wheel. At 26" the bottom bracket has plenty of room. The extra cushion will be appreciated by passengers and the cargo.

The motors i have been looking at have been in the 1000-3000w range. I am unsure on how many turns the motor should have.
Something else i have been wondering about is if running the batteries at 36v would allow for better efficiency hill climbing when i have heavy cargo. And then running at 72v when i am commuting. Is it worth seeking out a variable voltage controller such as the phaserunner for this purpose?

I am hoping to spend under $800cad for the motor and controller.

Would appreciate any help and direction, thanks

 

[Balmorhea]

Direct drive hub motors aren’t good at widely different speed regimes, unless they’re grossly overpowered. You get the hub for the speed you want to go, and then you stick pretty close to that speed. The moral of that story is that you aren’t going to get a direct drive hub system that is good at 45 kph unloaded and 20 kph heavily loaded, unless it is packing more power than you need for either job.

The mission profile you describe is a much better match for a crank motor like Bafang BBSHD than it is for any hub motor.

My suggestion is go for the hub motor, but make it top out at 35 kph or less. In that case, the performance and efficiency won’t be nearly as compromised when you’re going relatively slowly.

 

[MadRhino]

This bike is a gift at that price !
Long frames are great for conversion.

 

[dogman dan]

Lovely bike for $300! way to go. But for your intended use, the best bet would be a mid drive.

If you go with a very large DD motor, and 72v, then you'd have so much power it would run fine in 26" wheel though, and haul a trailer if you wish.

Personally, I'd try a 36v mid drive first. Your needs should be more towards getting there to work at max efficiency, rather than maximum fun. And 72v will be too fast for riding with big loads. So mid drive it, and figure on about 36 kph travel most of the time, because the bike will be hard to handle with a big load on it. 45 kph will be fine at times, but not carrying all the tools. You won't want 80 kph, with a powerful DD at 72v.

Later on, you might consider going 48v, so get a mid drive able to do 36 or 48v.

Another option you might consider later on, a front, geared type hub motor to add power, but not so much speed, to your mid drive when running extremely heavy. This would work for hauling loads even the mid drive would struggle with. Use it mostly just to get going, like uphill starts.

 

[john61ct]

Yes, I think that last is a good compromise for value if heavy loads and steep hills are involved at the same time.

Otherwise just mid-drive may be enough.

If you had bigger budget Lightning Rods worth checking out.

So jealous about that bargain, well played!

Is it safe to run a bike with regen as the only rear brake?

No.

 

[goatman]

you might be interested in this thread by rswannabe, I highly recommend it for you

https://endless-sphere.com/forums/viewtopic.php?f=6&t=103634

 

[goatman]

Yes, I think that last is a good compromise for value if heavy loads and steep hills are involved at the same time.

Otherwise just mid-drive may be enough.

If you had bigger budget Lightning Rods worth checking out.

So jealous about that bargain, well played!

Is it safe to run a bike with regen as the only rear brake?

No.

the phaserunner with a DD, I do all my braking with the adjustable regen and use my front brake if I need a little more or im at a slow roll.

my trike doesn't have a rear brake, it has a rear parking brake but it has disc brakes on the front.
is it safe to just use phaserunner regen on the back tire for braking? I don't know,
what would cause the regen to fail and if regen failed you might be screwed. I just grabbed my bike, didn't turn it on, pushed the regen button and the bike just rolls so I guess if your bms trips or the battery blows a fuse when your doing 30mph and need to stop
you might be in trouble but if you go to torque arm picture thread you might be able to make something like this
https://endless-sphere.com/forums/viewtopic.php?f=2&t=26444&hilit=torque+arm+picture+thread&start=150#p1201307

 

[MadRhino]

Would be good if some try emergency braking and measure their braking distance. Just making things clear here: Front brake is just about alone when stopping is a must to save your life. The shorter you brake, the lesser part of the job the rear brake does. A bike without a front brake does need more than twice as long to stop. So, better learn and use the front brake before a real emergency does happen.

It is a habit, and training, to master the front brake modulation. A good rider can stop very short with the rear wheel a few inches off the ground. You can get away pretty safe with front brake alone, but rear alone is a real danger.

 

[john61ct]

Yes I interpreted the question literally.

For sudden stops, emergency braking should not rely on the electronic stuff working.

If the controller etc went completely dark, battery shorted out in smoke and sparks,

you should still be able to stop just as well as usual, from the old school mechanical braking system.

Regen may be needed for say drag braking without your pads getting hot on long steep descents

but otherwise just an optional "extra" from a safety POV.

 

[MadRhino]

Back to topic: Building that frame is very easy, for it has a lot of room and stability. Building it mid drive, I would use the space between the seat post and the wheel to drive the left side, free from the crank and all limitations of BB drives. For a hub build, the frame is long enough to to be safe using a high power hub motor. It could even be built as a stoke monkey, using a geared hub as a mid drive for very slow, heavy cargo riding.

 

[NCC1941]

I'm also running regen as my only rear brake at the moment, though I intend to fix that in the future, just for the peace of mind.

With a good controller and batteries that can take high regen current, regen can be easily enough to handle 99% your everyday braking needs. But unless you go for a setup that's wildly overspec'd for all of your other design goals, regen isn't going to be strong enough for emergency / panic stops. And as others have mentioned, you don't want to rely on the electronics as your only source of braking anyway. Even if you don't end up using it often, you need to have, at the very least, a front traditional brake capable of bringing the bike to a rapid stop.

 

[Balmorhea]

I built a GMAC hub motor wheel this evening. It was my first experience with a non-freewheeled gear-reduced hub motor. It was a fight to make it go around so I could true it.

I know this feature is intentional, to enable regenerative braking from a geared motor. All the same, I lamented the degree to which it would fundamentally change cycling by removing coasting. Yes, direct drive hubs aren’t good at coasting; I have direct drive bikes and I get that. But this was a different thing. It made me think of one-pedal electric cars, and how whenever you aren’t accelerating, you’re braking.

 

[goatman]

if I program the phaserunners virtual electronic freewheeling with about 1amp into my DD, you coast like a bicycle should.

 

[dogman dan]

Brakes are part of why I suggested a mid drive. Then he does not need a smaller rear wheel.

If he does a single rear hub motor, just make it a bigger motor, with 26" wheel then he can keep his brakes. If he goes to 20" wheel in the back of that frame, he will change the height too much, and pedal drag on corners, etc.

If he does not like the idea of a big motor meaning he only has one rear gear, then put two hub motors on it. Rear DD, front geared. Use the front only when you must, heavy load, up the hill.

E-bike kit has low rpm hub motors, if that would be your desire. They don't make more torque, but will run more efficient at lower rpm than typical hub motors. They work great for cargo bikes that are not excessively overloaded. Might try one of those first, if you don't like a mid drive.